Filippo Lippi
Wikimedia Commons
On Christmas we celebrate the birth of Jesus the true Son of the one, true God. God, the Father, acknowledged Jesus as His “beloved Son, with whom I am well pleased” (Matthew 3:17) and Jesus spoke often of his father, “every one who acknowledges me before men, I also will acknowledge before my Father who is in heaven; but whoever denies me before men, I also will deny before my Father who is in heaven” (Matthew 10:32-33).
However, heresies persist regarding the relationship of Jesus and God. Some heresies, such as the heresy of Photinus, claimed that Jesus was a good man, leading a good life, thereby merited being called a son of God through adoption. We know this to be false. Jesus is the “only son from the Father” (John 1:14) (note John sates that Jesus is the only son “from” and not “of” the Father). Other heresies (of Photinus, Sabellius, and Arius) contended that Jesus began to exist in time and that he came into exist separate from and after the Father. This is contrary to Jesus proclamation that, “I and the Father are one” (John 10:30).
To Love and Truth 
It must have been difficult to entirely steer clear of heresy in the theologically formative years preceding 451, especially considering the differences between the Greek and Latin definitions of words coined to express theological concepts. God bless!
I bet it was like the Wild West for a few centuries. But ultimately the Church knows that Truth is not limited to what humans can understand.
I agree. However, many still do not understand. I believe society is losing the tools/skills needed to determine the difference between what is true and untrue.